Methods and systems for automatically rerouting logical circuit data from a logical circuit failure to a dedicated backup circuit in a data network

ABSTRACT

An example method involves rerouting a logical circuit from a first set of switches to a second set of switches to communicate data between network devices without breaking the logical circuit. The logical circuit includes variable communication paths, and the second set of switches are to form a route associated with the variable communication paths that is not predefined and that is dynamically defined at a time of automatic rerouting. The example method also involves detecting a failure of the logical circuit based on at least one of a committed information rate or a committed burst size having been exceeded. In addition, the data is rerouted from the logical circuit to a logical failover circuit in the data network in response to detecting the failure of the logical circuit. The logical failover circuit includes an alternative communication path to communicate the data.

PRIORITY APPLICATIONS

This is a continuation of U.S. patent application Ser. No. 12/334,248,filed Dec. 12, 2008, which is a continuation of U.S. patent applicationSer. No. 10/829,795, filed on Apr. 22, 2004, now U.S. Pat. No.7,466,646, all of which are hereby incorporated herein by reference intheir entireties.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent is related to U.S. patent application Ser. No. 10/348,077,entitled “Method and System for Obtaining Logical Performance Data for aCircuit in a Data Network,” filed on Jan. 21, 2003, and U.S. patentapplication Ser. No. 10/348,592, entitled “Method and System forProvisioning and Maintaining a Circuit in a Data Network,” filed on Jan.21, 2003. This patent is also related to and filed concurrently withU.S. patent application Ser. No. 10/745,117, entitled “Method And SystemFor Providing A Failover Circuit For Rerouting Logical Circuit Data In AData Network,” filed on Dec. 23, 2003, U.S. patent application Ser. No.10/745,170, entitled “Method And System For Automatically Identifying ALogical Circuit Failure In A Data Network,” filed on Dec. 23, 2003, and“Method And System For Automatically Rerouting Logical Circuit Data In AData Network,” filed on Dec. 23, 2003. All of the above-referencedapplications are assigned to the same assignee as this patent and areexpressly incorporated herein by reference.

FIELD OF THE DISCLOSURE

The present invention relates to the routing of data using logicalcircuits in a data network. More particularly, the present invention isrelated to automatically rerouting logical circuit data from a logicalcircuit failure to a dedicated backup circuit in a data network.

BACKGROUND

Data networks contain various network devices, such as switches, forsending and receiving data between two locations. For example, framerelay and Asynchronous Transfer Mode (“ATM”) networks containinterconnected network devices that allow data packets or cells to bechanneled over a circuit through the network from a host device to aremote device. For a given network circuit, the data from a host deviceis delivered to the network through a physical circuit such as a T1 linethat links to a switch of the network. The remote device thatcommunicates with the host through the network also has a physicalcircuit to a switch of the network. A network circuit also includes alogical circuit which includes a variable communication path for databetween the switches associated with the host and the remote device.

In large-scale networks, the host and remote end devices of a networkcircuit may be connected across different local access and transportareas (“LATAs”) which may in turn be connected to one or moreInter-Exchange Carriers (“IEC”) for transporting data between the LATAs.These connections are made through physical trunk circuits utilizingfixed logical connections known as Network-to-Network Interfaces(“NNIs”). For example, a network circuit from Birmingham to Miami mayhave connections from a host device in the Birmingham LATA to an IEC andthen from the IEC to a remote device in the Miami LATA.

Periodically, failures may occur to the trunk circuits or the NNIs ofnetwork circuits in large-scale networks causing lost data. Currently,such network circuit failures are handled by dispatching technicians oneach end of the network circuit (i.e., in each LATA) in response to areported failure. The technicians manually access a logical elementmodule to troubleshoot the logical circuit portion of the networkcircuit. The logical element module communicates with the switches inthe data network and provides the technician with the status of thelogical connections which make up the logical circuit. Once thetechnician determines the status of a logical connection at one end of alogical circuit (e.g., the host end), the technician then must access anetwork database to determine the location of the other end of thelogical circuit so that its status may also be ascertained. If thetechnician determines the logical circuit is operating properly, thetechnician then accesses a physical element module to troubleshoot thephysical circuit portion of the network circuit to determine the causeof the failure and then repair it.

In order to reduce downtime associated with repairing network circuits,some network circuit providers offer network circuit customers a “backupservice” plan. Currently, these backup service plans include providing abackup or standby physical circuit between a host device and a remotedevice for manually rerouting data from one or more failed logicalcircuits in a data network, until the primary network circuit has beenrepaired. However, current backup services provided by network circuitproviders do not offer backup logical circuits provisioned over thebackup physical circuit prior to a network circuit failure. Thus, abackup logical circuit must be manually provisioned over the backupphysical circuit after a failure is determined, before logical circuitdata may be rerouted from the failed network circuit. This provisioningprocess increases the time it will take to reroute the logical circuitdata over the backup logical circuits. Moreover, logical circuitsdesignated for backup service are identified by “services names” ratherthan the logical circuit identifiers typically required to identity andreroute logical circuits in a data network. As a result, prior torerouting data from an affected logical circuit, a technician mustmanually access a network database to determine the logical circuitidentifier associated with the circuit's “services name,” therebyfurther increasing the time before logical circuit data may be rerouted.

It is with respect to these considerations and others that the presentinvention has been made.

SUMMARY

In accordance with the present invention, the above and other problemsare solved by a method and system for automatically rerouting logicalcircuit data from a logical circuit failure to a dedicated backupcircuit in a data network. When a failure in a logical circuit isdetected, a label or services name associated with the logical circuitis automatically associated with a logical circuit identifier utilizedfor identifying the logical circuit in the data network. Once thelogical circuit is associated with the logical circuit identifier, thelogical circuit data may be automatically rerouted to a “failovernetwork,” thereby minimizing lost data until the failure in the logicalcircuit is resolved.

One method includes determining a failure in a logical circuit in thedata network. The logical circuit defines a communication path forcommunicating data. The method further includes automatically accessinga database to associate a label assigned to the failed logical circuitwith a logical circuit identifier for the failed logical circuit,identifying an existing logical failover circuit including an alternatecommunication path for communicating the data from the failed logicalcircuit, and rerouting the data from the failed logical circuit to thelogical failover circuit in the data network.

The method may further include, after rerouting the data to a logicalfailover circuit, determining whether the failure in the correspondinglogical circuit has been corrected, and if the failure has beencorrected, then rerouting the data from the logical failover circuitback to the logical circuit in the data network without manualintervention. The logical circuit identifier may be a data linkconnection identifier (“DLCI”) or a virtual path/virtual circuitidentifier (“VPI/VCI”). In rerouting the data to the logical failovercircuit in the data network, the method may further include reroutingthe data to a backup physical circuit for communicating the data for thelogical failover circuit. Each logical circuit may be either a permanentvirtual circuit (“PVC”) or a switched virtual circuit (“SVC”). The datanetwork may be either a frame relay or asynchronous transfer mode(“ATM”) network.

In accordance with other aspects, the present invention relates to asystem for automatically rerouting logical circuit data from a logicalcircuit failure to a dedicated backup circuit in a data network. Thesystem includes a network device for establishing a data communicationpath for the logical circuit in the data network and a logical elementmodule, in communication with the network device, for storing adatabase. The database stores one or more records which include a labelassociated with the logical circuit and a logical circuit identifier.The system further includes a network management module, incommunication with the logical element module, for determining a failurein the logical circuit, automatically accessing the database toassociate the label assigned with the logical circuit identifier,identifying an existing logical failover circuit including an alternatecommunication path for communicating the data from the failed logicalcircuit, rerouting the data from the failed logical circuit to thelogical failover circuit in the data network, after rerouting the datato the logical failover circuit, determining whether the failure in thelogical circuit has been corrected, and if the failure in the logicalcircuit has been corrected, then rerouting the data from the logicalfailover circuit to the logical circuit in the data network.

These and various other features as well as advantages, whichcharacterize the present invention, will be apparent from a reading ofthe following detailed description and a review of the associateddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a data network according to an embodiment of theinvention.

FIG. 2 illustrates a local access and transport area (“LATA”) in thedata network of FIG. 1, according to an embodiment of the invention.

FIG. 3 illustrates a network management system which may be utilized toautomatically rerouting logical circuit data from a logical circuitfailure to a dedicated backup circuit in the data network of FIG. 1,according to an embodiment of the invention.

FIG. 4 illustrates a failover data network for rerouting logical circuitdata in the data network of FIG. 1, according to an embodiment of theinvention.

FIG. 5 illustrates a flowchart describing logical operations forautomatically rerouting logical circuit data from a logical circuitfailure to a dedicated backup circuit in the data network of FIG. 1,according to an embodiment of the invention.

DETAILED DESCRIPTION

Embodiments of the present invention provide for a method and system forautomatically rerouting logical circuit data from a logical circuitfailure to a dedicated backup circuit in a data network. When a failurein a logical circuit is detected, a label or services name associatedwith the logical circuit is automatically associated with a logicalcircuit identifier utilized for identifying the logical circuit in thedata network. Once the logical circuit is associated with the logicalcircuit identifier, the logical circuit data may be automaticallyrerouted to a “failover network,” thereby minimizing lost data until thefailure in the logical circuit is resolved. In the following detaileddescription, references are made to the accompanying drawings that forma part hereof, and in which are shown by way of illustration specificembodiments or examples. Referring now to the drawings, in which likenumerals represent like elements through the several figures, aspects ofthe present invention and the exemplary operating environment will bedescribed.

Embodiments of the present invention may be generally employed in a datanetwork 2 as shown in FIG. 1. The data network 2 includes local accessand transport areas (“LATAs”) 5 and 15 which are connected by anInter-Exchange Carrier (“IEC”) 10. It should be understood that theLATAs 5 and 15 may be data networks operated by a commonly owned LocalExchange Carrier (“LEC”). It should be further understood that the IEC10 may include one or more data networks which may be operated by acommonly owned IEC. It will be appreciated by those skilled in the artthat the data network 2 may be a frame relay network, asynchronoustransfer mode (“ATM”) network, or any other network capable ofcommunicating data conforming to Layers 24 of the Open SystemsInterconnection (“OSI”) model developed by the International StandardsOrganization, incorporated herein by reference. It will be appreciatedthat these networks may include, but are not limited to, communicationsprotocols conforming to the Multiprotocol Label Switching Standard(“MPLS”) networks and the Transmission Control Protocol/InternetProtocol (“TCP/IP”), which are known to those skilled in the art.

The data network 2 includes a network circuit which channels databetween a host device 112 and a remote device 114 through the LATA 5,the IEC 10, and the LATA 15. It will be appreciated by those skilled inthe art that the host and remote devices 112 and 114 may be local areanetwork (LAN) routers, LAN bridges, hosts, front end processors, FrameRelay Access Devices (FRADs), or any other device with a frame relay,ATM, or network interface. It will be further appreciated that in thedata network 2, the LATAs 5 and 15 and the IEC 10 may include networkelements (not shown) which support interworking to enable communicationsbetween host and remote devices supporting dissimilar protocols. Networkelements in a data network supporting interworking may translate framerelay data packets or frames sent from a host FRAD to ATM data packetsor cells so that a host device may communicate with a remote devicehaving an ATM interface. The LATAs 5 and 15 and the IEC 10 may furtherinclude one or more interconnected network elements, such as switches(not shown), for transmitting data. An illustrative LATA data networkwill be discussed in greater detail in the description of FIG. 2 below.

The network circuit between the host device 112 and the remote device114 in the data network 2 includes a physical circuit and a logicalcircuit. As used in the foregoing description and the appended claims, aphysical circuit is defined as the physical path that connects the endpoint of a network circuit to a network device. For example, thephysical circuit of the network circuit between the host device 112 andthe remote device 114 includes the physical connection 121 between thehost device 112 and the LATA 5, the physical connection 106 between theLATA 5 and the IEC 10, the physical connection 108 between the IEC 10and the LATA 15, and the physical connection 123 between the LATA 15 andthe remote device 114.

It should be understood that the host and remote devices may beconnected to the physical circuit described above using user-to-networkinterfaces (“UNIs”). As is known to those skilled in the art, an UNI isthe physical demarcation point between a user device (e.g, a hostdevice) and a public data network. It will further be understood bythose skilled in the art that the physical connections 106 and 108 mayinclude trunk circuits for carrying the data between the LATAs 5 and 15and the IEC 10. It will be further understood by those skilled in theart that the connections 121 and 123 may be any of various physicalcommunications media for communicating data such as a 56 Kbps line or aT1 line carried over a four-wire shielded cable or over a fiber opticcable.

As used in the foregoing description and the appended claims, a logicalcircuit is defined as a portion of the network circuit wherein data issent over variable communication data paths or logical connectionsestablished between the first and last network devices within a LATA orIEC network and over fixed communication data paths or logicalconnections between LATAs (or between IECs). Thus, no matter what paththe data takes within each LATA or IEC, the beginning and end of eachlogical connection between networks will not change. For example, thelogical circuit of the network circuit in the data network 2 may includea variable communication path within the LATA 5 and a fixedcommunication path (i.e., the logical connection 102) between the LATA 5and the IEC 10. It will be understood by those skilled in the art thatthe logical connections 102 and 104 in the data network 2 may includenetwork-to-network interfaces (“NNIs”) between the last sending switchin a LATA and the first receiving switch in an IEC.

As is known to those skilled in the art, each logical circuit in a datanetwork may be identified by a unique logical identifier. In frame relaynetworks, the logical identifier is called a Data Link ConnectionIdentifier (“DLCI”) while in ATM networks the logical identifier iscalled a Virtual Path Identifier/Virtual Circuit Identifier (“VPI/VCI”).In frame relay networks, the DLCI is a 10-bit address field contained inthe header of each data frame and contains identifying information forthe logical circuit as well as information relating to the destinationof the data in the frame and service parameters for handling networkcongestion. For example, in the data network 2 implemented as a framerelay network, the designation DLCI 100 may be used to identify thelogical circuit between the host device 112 and the remote device 114.It will be appreciated that in data networks in which logical circuitdata is communicated through more than one carrier (e.g., an LEC and anIEC) the DLCI designation for the logical circuit may change in aspecific carrier's network. For example, in the data network 2, thedesignation DLCI 100 may identify the logical circuit in the LATA 5 andLATA 15 but the designation DLCI 800 may identify the logical circuit inthe IEC 10.

Illustrative service parameters which may be included in the DLCIinclude a Committed Information Rate (“CIR”) parameter and a CommittedBurst Size (“Bc”) parameter. As is known to those skilled in the art,the CIR represents the average capacity of the logical circuit and theBc represents the maximum amount of data that may be transmitted. Itwill be appreciated that the logical circuit may be provisioned suchthat when the CIR or the Bc is exceeded, the receiving switch in thedata network will discard the frame. It should be understood that thelogical circuit parameters are not limited to CIR and Bc and that otherparameters known to those skilled in the art may also be provisioned,including, but not limited to, Burst Excess Size (“Be”) and CommittedRate Measurement Interval (“Tc”). In ATM networks, the VPI/VCI is anaddress field contained in the header of each ATM data cell and containsidentifying information for the logical circuit as well as informationspecifying a data cell's destination and specific bits which mayindicate, for example, the existence of congestion in the network and athreshold for discarding cells.

It should be understood that the logical circuit in the data network 2may be a permanent virtual circuit (“PVC”) available to the network atall times or a temporary or a switched virtual circuit (“SVC”) availableto the network only as long as data is being transmitted. It should beunderstood that the data network 2 may further include additionalswitches or other interconnected network elements (not shown) creatingmultiple paths within each LATA and IEC for defining each PVC or SVC inthe data network. It will be appreciated that the data communicated overthe logical connections 102 and 104 may be physically carried by thephysical connections 106 and 108.

The data network 2 may also include a failover network 17 for reroutinglogical circuit data, according to an embodiment of the invention. Thefailover network 17 may include a network failover circuit includingbackup physical connections 127 and 129, physical connections 134 and144 and logical connections 122 and 132 for rerouting logical circuitdata in the event of a failure in the network circuit between the hostdevice 112 and the remote device 114. The failover network 17 will bedescribed in greater detail in the description of FIG. 4 below. The datanetwork 2 may also include a network management system 175 incommunication with the LATA 5, the LATA 15, and the failover network 17.The network management system 175 may be utilized to obtain statusinformation for the logical and physical circuit between the host device112 and the remote device 114. The network management system 175 mayalso be utilized for rerouting logical data in the data network 2between the host device 112 and the remote device 114. The networkmanagement system 175 will be discussed in greater detail in thedescription of FIG. 3 below.

FIG. 2 illustrates the LATA 5 in the data network 2 described in FIG. 1above, according to an embodiment of the present invention. As shown inFIG. 2, the LATA 5 includes interconnected network devices such asswitches 186, 187, and 188. It will be appreciated that the data network2 may also contain other interconnected network devices and elements(not shown) such as digital access and cross connect switches (“DACS”),channel service units (“CSUs”), and data service units (“DSUs”). Asdiscussed above in the description of FIG. 1, the connection data pathsof a logical circuit within a data network may vary between the firstand last network devices in a data network. For example, as shown inFIG. 2, the logical circuit in the LATA 5 may include the communicationpath 185 between the switches 186 and 188 or the communication path 184between the switches 186, 187, and 188. As discussed above, it should beunderstood that the actual path taken by data through the LATA 5 is notfixed and may vary from time to time, such as when automatic reroutingtakes place.

It will be appreciated that the switches 186, 187, and 188 may include asignaling mechanism for monitoring and signaling the status of thelogical circuit in the data network 2. Each time a change in the statusof the logical circuit is detected (e.g., a receiving switch beginsdropping frames), the switch generates an alarm or “trap” which may thenbe communicated to a management station, such as a logical elementmodule (described in detail in the description of FIG. 3 below), in thenetwork management system 175. In one embodiment, the signalingmechanism may be in accord with a Local Management Interface (“LMI”)specification, which provides for the sending and receiving of “statusinquiries” between a data network and a host or remote device. The LMIspecification includes obtaining status information through the use ofspecial management frames (in frame relay networks) or cells (in ATMnetworks). In frame relay networks, for example, the special managementframes monitor the status of logical connections and provide informationregarding the health of the network. In the data network 2, the host andremote devices 112 and 114 receive status information from theindividual LATAs they are connected to in response to a status requestsent in a special management frame or cell. The LMI status informationmay include, for example, whether or not the logical circuit iscongested or whether or not the logical circuit has failed. It should beunderstood that the parameters and the signaling mechanism discussedabove are optional and that other parameters and mechanisms may also beutilized to obtain connection status information for a logical circuit.

FIG. 3 illustrates the network management system 175 which may beutilized to automatically reroute logical circuit data from a physicalcircuit failure in the data network of FIG. 1, according to anembodiment of the invention. The network management system 175 includesa service order system 160, a network database 170, a logical elementmodule 153, a physical element module 155, a network management module176, and a test module 180. The service order system 160 is utilized inthe data network 2 for receiving service orders for provisioning networkcircuits. The service order includes information defining thetransmission characteristics (i.e., the logical circuit) of the networkcircuit. The service order also contains the access speed, CIR, burstrates, and excess burst rates. The service order system 160 communicatesthe service order information to a network database 170 over managementtrunk 172. The network database 170 assigns and stores the parametersfor the physical circuit for the network circuit such as a port numberon the switch 186 for transmitting data over the physical connection 121to and from the host device 112.

The network database 170 may also be in communication with an operationssupport system (not shown) for assigning physical equipment to thenetwork circuit and for maintaining an inventory of the physicalassignments for the network circuit. An illustrative operations supportsystem is “TIRKS”® (Trunks Integrated Records Keeping System) marketedby TELECORDIA™ TECHNOLOGIES, Inc. of Morristown, N.J. The networkdatabase 170 may also be in communication with a Work ForceAdministration and Control system (“WFA/C”) (not shown) used to assignresources (i.e., technicians) to work on installing the physicalcircuit.

The network management system 175 also includes the logical elementmodule 153 which is in communication with the switches in the datanetwork 2 through management trunks 183. The logical element module 153runs a network management application program to monitor the operationof logical circuits which includes receiving trap data generated by theswitches which indicate the status of logical connections. The trap datamay be stored in the logical element module 153 for later analysis andreview. The logical element module 153 is also in communication with thenetwork database 170 via management trunks 172 for accessing informationregarding logical circuits such as the logical identifier data. Thelogical identifier data may include, for example, the DLCI or VPI/VCIheader information for each data frame or cell in the logical circuitincluding the circuit's destination and service parameters. The logicalelement module 153 may consist of terminals (not shown) that display amap-based graphical user interface (“GUI”) of the logical connections inthe data network. An illustrative logical element module is theNAVISCORE™ system marketed by LUCENT TECHNOLOGIES, Inc. of Murray Hill,N.J.

The network management system 175 further includes the physical elementmodule 155 in communication with the physical connections of the networkcircuit via management trunks (not shown). The physical element module155 runs a network management application program to monitor theoperation and retrieve data regarding the operation of the physicalcircuit. The physical element module 155 is also in communication withthe network database 170 via management trunks 172 for accessinginformation regarding physical circuits, such as line speed. Similar tothe logical element module 153, the physical logical element module 155may also consist of terminals (not shown) that display a map-basedgraphical user interface (“GUI”) of the physical connections in the LATA5. An illustrative physical element module is the Integrated Testing andAnalysis System (“INTAS”), marketed by TELECORDIA™ TECHNOLOGIES, Inc. ofMorristown, N.J., which provides flow-through testing and analysis oftelephony services.

The physical element module 155 troubleshoots the physical connectionsfor a physical circuit by communicating with test module 180, whichinterfaces with the physical connections via test access point 156. Thetest module 180 obtains the status of the physical circuit bytransmitting “clean” test signals to test access point 156 (shown inFIG. 2) which “loops back” the signals for detection by the test module180. It should be understood that there may be multiple test accesspoints on each of the physical connections for the physical circuit.

The network management system 175 further includes the networkmanagement module 176 which is in communication with the service ordersystem 160, the network database 170, the logical element module 153,and the physical element module 155 through communications channels 172.It should be understood that in one embodiment, the network managementsystem 176 may also be in communication with the LATA 15, the IEC 10,and the failover network 17. The communications channels 172 may be on alocal area network (“LAN”). The network management module 176 mayconsist of terminals (not shown), which may be part of a general-purposecomputer system that displays a map-based graphical user interface(“GUI”) of the logical connections in data networks. The networkmanagement module 175 may communicate with the logical element module153 and the physical element module 155 using a Common Object RequestBroker Architecture (“CORBA”). As is known to those skilled in the art,CORBA is an open, vendor-independent architecture and infrastructurewhich allows different computer applications to work together over oneor more networks using a basic set of commands and responses. Thenetwork management module 176 may also serve as an interface forimplementing logical operations to provision and maintain networkcircuits. The logical operations may be implemented as machineinstructions stored locally or as instructions retrieved from thelogical and physical element modules 153 and 155. An illustrative methoddetailing the provisioning and maintenance of network circuits in a datanetwork is presented in U.S. patent application Ser. No. 10/348,592,entitled “Method And System For Provisioning And Maintaining A CircuitIn A Data Network,” filed on Jan. 23, 2003, and assigned to the sameassignee as this patent, which is expressly incorporated herein byreference. An illustrative network management module is the BroadbandNetwork Management System® (BBNMS) marketed by TELECORDIA™ TECHNOLOGIES,Inc. of Morristown, N.J.

FIG. 4 illustrates a failover data network for rerouting logical circuitdata, according to one embodiment of the present invention. As shown inFIG. 4, the failover network 17 includes an IEC 20, a LATA 25, and anIEC 30. The failover network further includes a network failover circuitwhich includes a physical failover circuit and a logical failovercircuit. The physical failover circuit includes the backup physicalconnection 127 between the host device 112 and the LATA 5 (shown in FIG.1), the physical connection 134 between the LATA 5 (shown in FIG. 1) andthe IEC 20, the physical connection 136 between the IEC 20 and the LATA25, the physical connection 138 between the LATA 25 and the IEC 30, thephysical connection 144 between the IEC 30 and the LATA 15 (shown inFIG. 1), and the physical connection 129 between the LATA 15 and theremote device 114. Similarly, the logical failover circuit may includethe logical connection 122 between the LATA 5 (shown in FIG. 1) and theIEC 20, the logical connection 124 between the IEC 20 and the LATA 25,the logical connection 126 between the LATA 25 and the IEC 30, and thelogical connection 132 between the IEC 30 and the LATA 15 (shown in FIG.1). It should be understood that in one embodiment, the network failovercircuit illustrated in the failover network 17 may include a dedicatedphysical circuit and a dedicated logical circuit provisioned by anetwork service provider serving the LATAs 5, 15, and 25 and the IECs 20and 30, for rerouting logical data from a failed logical circuit.

FIG. 5 illustrates a flowchart describing logical operations 500 forautomatically rerouting logical circuit data from a logical circuitfailure to a dedicated backup circuit in a data network, according to anembodiment of the invention. It will be appreciated that the logicaloperations 500 may be initiated by a customer report of a networkcircuit failure received in the data network 2. For example, a customerat the remote device 114 may determine that the remote device 114 is notreceiving any data (e.g., frames or cells) sent from the host device 112(e.g., by reviewing LMI status information in the host device). Afterreceiving the customer report, the network service provider providingthe network circuit may open a trouble ticket in the service ordersystem 160 to troubleshoot the logical circuit. It will be appreciatedthat, in one embodiment, the logical circuit of the network circuit maybe associated with a network “backup service” for rerouting data to adedicated backup network circuit in the data network 2. For example, thebackup network circuit may include the backup physical connections 127and 129 between the host device 112 and the remote device 114. Thoseskilled in the art will appreciate that the logical circuit associatedwith the backup service may be associated with a label also known as a“services name.”

The logical operations 500 begin at operation 505 where the networkmanagement module 176 determines whether a logical circuit failure hasoccurred. It will be appreciated that in one embodiment, thisdetermination may be made by the network management module 176communicating with the logical element module 153 to request trap datagenerated by one or more switches in the data network which indicate thestatus of one or more logical connections making up the logical circuit.It should be understood that a logical circuit failure occurs when oneor more logical connections in a logical circuit have failed. Asdiscussed above in the description of FIG. 2, trap data indicating alogical connection failure may include status information indicatingthat a switch in the data network is discarding frames or cells. Such anevent may occur, for example, when the maximum CIR or Bc (as specifiedin the DLCI of a frame in a frame relay network, for example) isexceeded. For example, in the data network 2 shown in FIG. 1, the “X”marking the logical connections 102 and 104 indicate that bothconnections are “down beyond” (i.e., not communicating data) the NNIsfor the logical circuit in the LATA data networks 5 and 15. In thisexample, such a condition may indicate that the logical circuit failurelies in the IEC data network 10. The logical operations 500 thencontinue from operation 505 to operation 510.

At operation 510, the network management module 176 accesses thedatabase in the logical element module 153 to identify the logicalcircuit identifier associated with the label or services name associatedwith the failed physical circuit. It will be appreciated that thenetwork management module 176 may be configured to automaticallyidentify the logical circuit identifier by accessing a database in thelogical element module 153 or in the network database 170, which listsservice names for logical circuits along with their correspondinglogical circuit identifications. The logical operations 500 thencontinue from operation 510 to operation 515.

At operation 515, the network management module 176 identifies anexisting logical failover circuit for rerouting the data from the failedlogical circuit in the data network. It will be appreciated that in oneembodiment, the logical failover circuit selected may be a dedicatedlogical circuit provisioned in a backup physical circuit in the datanetwork 2. For example, as shown in FIG. 1, the logical failover circuitmay communicate data over a backup physical circuit including thephysical connections 127, 124, 134, and 129. The logical operations 500then continue from operation 515 to operation 520.

At operation 520 the network management module 176 reroutes the datafrom the failed logical circuit to the logical failover circuit. It willbe appreciated that the reroute of the data may be accomplished from thelogical management module 153 or the network management module 176which, in communication with the switches in the data network 2 (and thefailover network 17), sends instructions to reroute the logical datafrom the NNIs or logical connections 102 and 104 to the failover NNIs orlogical connections 122, 124, 126, and 132 in the logical failovercircuit. The logical operations 500 then continue from operation 520 tooperation 525.

At operation 525, the network management module 176 determines thefailed logical circuit has been restored. This determination may bemade, for example, by continuous or periodic logical circuit monitoringof the link status of the failed logical circuit, which may be performedby the logical element module 153 in communication with the networkmanagement module 176, to establish that the logical connections 102 (atthe LATA 5) and 104 (at the LATA 15) are successfully communicatingdata. If at operation 525 it is determined that the failed logicalcircuit has not been restored, the logical operations 500 return tooperation 520 where the rerouting of the data is maintained on thelogical failover circuit. If however, at operation 525, it is determinedthat the failed logical circuit has been restored (i.e., the primaryphysical circuit has been repaired), then the logical operations 525continue to operation 530 where the data on the logical failover circuitis rerouted back to the restored logical circuit. Similar to thererouting of the logical data onto the logical failover circuit, thererouting of the logical data back onto the restored logical circuit maybe accomplished from the network management module 176 which, incommunication with the switches in the data network 2 (and the failovernetwork 17) sends instructions to reroute the data from the failoverNNIs or logical connections 122, 124, 126, and 132 to the restored NNIsor logical connections 102 and 104 in the restored logical circuit. Thelogical operations 500 then end.

It will be appreciated that the embodiments of the invention describedabove provide for a method and system for automatically reroutinglogical circuit data from a logical circuit failure to a dedicatedbackup circuit in a data network. When a failure in a logical circuit isdetected, a label or services name associated with the logical circuitis automatically associated with a logical circuit identifier utilizedfor identifying the logical circuit in the data network. Once thelogical circuit is associated with the logical circuit identifier, thelogical circuit data may be automatically rerouted to a “failovernetwork,” thereby minimizing lost data until the failure in the logicalcircuit is resolved. The various embodiments described above areprovided by way of illustration only and should not be construed tolimit the invention. Those skilled in the art will readily recognizevarious modifications and changes that may be made to the presentinvention without following the example embodiments and applicationsillustrated and described herein, and without departing from the truespirit and scope of the present invention, which is set forth in thefollowing claims.

What is claimed is:
 1. A method of rerouting data, comprising: reroutinga logical circuit from a first set of switches to a second set ofswitches to communicate data between network devices without breakingthe logical circuit, the logical circuit comprising variablecommunication paths, and the second set of switches to form a routeassociated with the variable communication paths that is not predefinedand that is dynamically defined at a time of automatic rerouting;detecting a failure of the logical circuit based on at least one of acommitted information rate or a committed burst size having beenexceeded; and rerouting the data from the logical circuit to a logicalfailover circuit in the data network in response to detecting thefailure of the logical circuit, wherein the logical failover circuitcomprises an alternative communication path to communicate the data. 2.A method as defined in claim 1, wherein the logical circuit comprisesvariable logical connections.
 3. A method as defined in claim 1, whereinthe logical failover circuit comprises a dedicated physical circuit anda dedicated logical circuit.
 4. A method as defined in claim 1, furthercomprising determining that the at least one of the committedinformation rate or the committed burst size has been exceeded by:receiving a header associated with the data communicated via the logicalcircuit; and determining the exceeded committed information rate or theexceeded committed burst size based on threshold information in theheader.
 5. A method as defined in claim 1, further comprising: receivinga service order specifying the at least one of the committed informationrate or the committed burst size; and provisioning the logical circuitbased on the at least one of the committed information rate or thecommitted burst size.
 6. A method as defined in claim 1, furthercomprising receiving trap data generated by a network switch, anddetermining the exceeded committed information rate or the exceededcommitted burst size based on the trap data.
 7. A method as defined inclaim 6, wherein the network switch generates the trap data in responseto detecting dropped data.
 8. A method as defined in claim 1, furthercomprising: communicating a test signal to at least one of a pluralityof test points associated with the logical circuit; and receiving a loopback signal from the at least one of the plurality of test pointsindicating the exceeded committed information rate or the exceededcommitted burst size.
 9. A method as defined in claim 1, furthercomprising determining the exceeded committed information rate or theexceeded committed burst size based on a customer report of a networkcircuit failure.
 10. A system to reroute data, comprising: a processor;and a memory storing machine readable instructions that cause theprocessor to perform a method comprising: rerouting a logical circuitfrom a first set of switches to a second set of switches to communicatedata between network devices while maintaining the logical circuit, thelogical circuit comprising variable communication paths, and the secondset of switches to form a route associated with the variablecommunication paths that is not predefined and that is dynamicallydefined at a time of automatic rerouting of the variable communicationpaths; detecting a failure of the logical circuit based on at least oneof a committed information rate or a committed burst size having beenexceeded; and rerouting the data from the logical circuit to a logicalfailover circuit in the data network in response to detecting thefailure of the logical circuit, wherein the logical failover circuitcomprises an alternative communication path to communicate the data. 11.A system as defined in claim 10, wherein the method further comprises:receiving a service order specifying the at least one of the committedinformation rate or the committed burst size; and provisioning thelogical circuit based on the at least one of the committed informationrate or the committed burst size.
 12. A system as defined in claim 10,wherein the method further comprises receiving trap data generated by anetwork switch, and determining the exceeded committed information rateor the exceeded committed burst size based on the trap data.
 13. Asystem as defined in claim 12, wherein the network switch generates thetrap data in response to detecting dropped data.
 14. A system as definedin claim 10, wherein the method further comprises communicating a testsignal to at least one of the plurality of test points, and receiving aloop back signal from the at least one of the plurality of test points,the loop back signal being indicative of the exceeded committedinformation rate or the exceeded committed burst size.
 15. A tangiblemachine accessible storage device or storage disc comprisinginstructions that cause a machine to perform a method comprising:rerouting a logical circuit from a first set of switches to a second setof switches to communicate data between network devices in an absence ofa failure of the logical circuit, the logical circuit comprisingvariable communication paths, and the second set of switches to form aroute associated with the variable communication paths that is notpredefined and that is dynamically defined at a time at which thevariable communication paths are automatically rerouted whilemaintaining the logical circuit through the second set of switches;detecting a failure of the logical circuit based on at least one of acommitted information rate or a committed burst size having beenexceeded; and rerouting the data from the logical circuit to a logicalfailover circuit in the data network in response to detecting thefailure of the logical circuit, wherein the logical failover circuitcomprises an alternative communication path to communicate the data. 16.A tangible machine accessible storage device or storage disc as definedin claim 15, wherein the method further comprises determining theexceeded committed information rate or the exceeded committed burst sizeby: receiving a header associated with the data communicated via thelogical circuit; and determining the exceeded committed information rateor the exceeded committed burst size based on threshold information inthe header.
 17. A tangible machine accessible storage device or storagedisc as defined in claim 15, wherein the method further comprisesdetermining the exceeded committed information rate or the exceededcommitted burst size by: communicating a test signal to at least one ofa plurality of test points associated with the logical circuit; andreceiving a loop back signal from the at least one of the plurality oftest points, wherein the loop back signal is indicative of the exceededcommitted information rate or the exceeded committed burst size.
 18. Atangible machine accessible storage device or storage disc as defined inclaim 15, wherein the method further comprises receiving trap datagenerated by a network switch, and determining the exceeded committedinformation rate or the exceeded committed burst size based on the trapdata.
 19. A tangible machine accessible storage device or storage discas defined in claim 18, wherein the network switch generates the trapdata in response to detecting dropped data.
 20. A tangible machineaccessible storage device or storage disc as defined in claim 15,wherein the method further comprises determining the exceeded committedinformation rate or the exceeded committed burst size based on acustomer report of a network circuit failure.